Ten-eleven Translocation Proteins Research Articles

Drosophila TET acts with PRC1 to activate gene expression independently of its catalytic activity.

Enzymes of the ten-eleven translocation (TET) family play a key role in the regulation of gene expression by oxidizing 5-methylcytosine (5mC), a prominent epigenetic mark in many species. Yet, TET proteins also have less characterized noncanonical modes of action, notably in Drosophila, whose genome is devoid of 5mC. Here, we show that Drosophila TET activates the expression of genes required for larval central nervous system (CNS) development mainly in a catalytic-independent manner. Genome-wide profiling shows that TET is recruited to enhancer and promoter regions bound by Polycomb group complex (PcG) proteins. We found that TET interacts and colocalizes on chromatin preferentially with Polycomb repressor complex 1 (PRC1) rather than PRC2. Furthermore, PRC1 but not PRC2 is required for the activation of TET target genes. Last, our results suggest that TET and PRC1 binding to activated genes is interdependent. These data highlight the importance of TET noncatalytic function and the role of PRC1 for gene activation in the Drosophila larval CNS.

Genetic Mechanisms Driving Uterine Leiomyoma Pathobiology, Epidemiology, and Treatment.

Uterine leiomyomas (ULs) are the most common benign tumor of the uterus. They can be associated with symptoms including abnormal uterine bleeding, pelvic pain, urinary frequency, and pregnancy complications. Despite the high prevalence of UL, its underlying pathophysiology mechanisms have historically been poorly understood. Several mechanisms of pathogenesis have been suggested, implicating various genes, growth factors, cytokines, chemokines, and microRNA aberrations. The purpose of this study is to summarize the current research on the relationship of genetics with UL. Specifically, we performed a literature review of published studies to identify how genetic aberrations drive pathophysiology, epidemiology, and therapeutic approaches of UL. With regards to pathophysiology, research has identified MED12 mutations, HMGA2 overexpression, fumarate hydratase deficiency, and cytogenetic abnormalities as contributors to the development of UL. Additionally, epigenetic modifications, such as histone acetylation and DNA methylation, have been identified as contributing to UL tumorigenesis. Specifically, UL stem cells have been found to contain a unique DNA methylation pattern compared to more differentiated UL cells, suggesting that DNA methylation has a role in tumorigenesis. On a population level, genome-wide association studies (GWASs) and epidemiologic analyses have identified 23 genetic loci associated with younger age at menarche and UL growth. Additionally, various GWASs have investigated genetic loci as potential drivers of racial disparities in UL incidence. For example, decreased expression of Cytohesin 4 in African Americans has been associated with increased UL risk. Recent studies have investigated various therapeutic options, including ten-eleven translocation proteins mediating DNA methylation, adenovirus vectors for drug delivery, and "suicide gene therapy" to induce apoptosis. Overall, improved understanding of the genetic and epigenetic drivers of UL on an individual and population level can propel the discovery of novel therapeutic options.

Micronutrient regulation of the DNA methylome

The formation, inheritance, and removal of DNA methylation in the genome of mammalian cells is directly regulated by two families of enzymes–DNA methyltransferases (DNMTs) and Ten-Eleven Translocation proteins (TETs). DNMTs generate and maintain the inheritance of 5-methylcytosine (5mC), which is the substrate targeted by the TET enzymes for conversion to 5-hydroxymethylcytosine (5hmC) and its downstream oxidized derivatives. The activity of DNMT and TET is dependent on the availability of micronutrients and metabolite co-factors, including essential vitamins, amino acids, and trace metals, highlighting how DNA methylation levels can be directly enhanced, suppressed, or remodeled via metabolic and nutritional perturbations. Dynamic changes in DNA methylation are required during embryonic development, lineage specification, and maintenance of somatic cell function that can be fine-tuned based on the influence of essential micronutrients. As we age, DNA methylation and hydroxymethylation levels drift in patterning, leading to epigenetic dysregulation and genomic instability that underlies the formation and progression of multiple diseases including cancer. Understanding how DNA methylation can be regulated by micronutrients will have important implications for the maintenance of normal tissue function upon aging, and in the prevention and treatment of diseases for improved health and lifespan.

Deciphering the TET3 interactome in primary thymic developing T cells

Ten-eleven translocation (TET) proteins are DNA dioxygenases that mediate active DNA demethylation. TET3 is the most highly expressed TET protein in thymic developing Tcells. TET3, either independently or in cooperation with TET1 or TET2, has been implicated in Tcell lineage specification by regulating DNA demethylation. However, TET-deficient mice exhibit complex phenotypes, suggesting that TET3 exerts multifaceted roles, potentially by interacting with other proteins. We performed liquid chromatography with tandem mass spectrometry in primary developing Tcells to identify TET3 interacting partners in endogenous, invivo conditions. We discover TET3 interacting partners. Our data establish that TET3 participates in a plethora of fundamental biological processes, such as transcriptional regulation, RNA polymerase elongation, splicing, DNA repair, and DNA replication. This resource brings in the spotlight emerging functions of TET3 and sets the stage for systematic studies to dissect the precise mechanistic contributions of TET3 in shaping Tcell biology.

Niche Tet maintains germline stem cells independently of dioxygenase activity

Ten-eleven translocation (TET) proteins are dioxygenases that convert 5-methylcytosine (5mC) into 5-hydroxylmethylcytosine (5hmC) in DNA and RNA. However, their involvement in adult stem cell regulation remains unclear. Here, we identify a novel enzymatic activity-independent function of Tet in the Drosophila germline stem cell (GSC) niche. Tet activates the expression of Dpp, the fly homologue of BMP, in the ovary stem cell niche, thereby controlling GSC self-renewal. Depletion of Tet disrupts Dpp production, leading to premature GSC loss. Strikingly, both wild-type and enzyme-dead mutant Tet proteins rescue defective BMP signaling and GSC loss when expressed in the niche. Mechanistically, Tet interacts directly with Bap55 and Stat92E, facilitating recruitment of the Polybromo Brahma associated protein (PBAP) complex to the dpp enhancer and activating Dpp expression. Furthermore, human TET3 can effectively substitute for Drosophila Tet in the niche to support BMP signaling and GSC self-renewal. Our findings highlight a conserved novel catalytic activity-independent role of Tet as a scaffold protein in supporting niche signaling for adult stem cell self-renewal.

TET Enzymes in the Immune System: From DNA Demethylation to Immunotherapy, Inflammation, and Cancer.

Ten-eleven translocation (TET) proteins are iron-dependent and α-ketoglutarate-dependent dioxygenases that sequentially oxidize the methyl group of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). All three epigenetic modifications are intermediates in DNA demethylation. TET proteins are recruited by transcription factors and by RNA polymerase II to modify 5mC at enhancers and gene bodies, thereby regulating gene expression during development, cell lineage specification, and cell activation. It is not yet clear, however, how the established biochemical activities of TET enzymes in oxidizing 5mC and mediating DNA demethylation relate to the known association of TET deficiency with inflammation, clonal hematopoiesis, and cancer. There are hints that the ability of TET deficiency to promote cell proliferation in a signal-dependent manner may be harnessed for cancer immunotherapy. In this review, we draw upon recent findings in cells of the immune system to illustrate established as well as emerging ideas of how TET proteins influence cellular function. Expected final online publication date for the Annual Review of Immunology, Volume 42 is April 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Tet1/DLL3/Notch1 signal pathway affects hippocampal neurogenesis and regulates depression-like behaviour in mice

Ten-eleven translocation protein 1 (Tet1) is associated with the regulation of depression-like behaviour in mice. However, the mechanism by which Tet1 affects neurogenesis in mice to regulate depression-like behaviours remains unclear. In this study, the chronic social defeat stress (CSDS) paradigm was constructed by overexpressing Tet1 protein in the mouse hippocampus, and 5-ethynyl-2′-deoxyuridine (EdU, 50 mg/kg) was injected on the seventh day to explore the mechanism of the regulation of the Tet1/Delta-like protein 3 (DLL3)/Notch1 protein pathway in mice hippocampal neurogenesis and its influence on depression-like behaviour. Following CSDS, the expression level of Tet1 decreased significantly. Moreover, due to the downregulation of Tet1 protein, the maintenance of the DNA methylation and demethylation balance was affected, resulting in a significant increase in the methylation levels of Notch1 and DLL3 and a significant decrease in the protein expression levels of DLL3, Notch1, and brain-derived neurotrophic factor (BDNF). At the same time, the proliferation and differentiation of neurones were affected, which was related to a significant decrease in the number of EdU+, doublecortin (DCX)+, and Ki67+ cells in the hippocampus of the CSDS model mice. When the Tet1 protein was overexpressed in the mouse hippocampus, DLL3 and Notch1 protein expression levels were upregulated, promoting hippocampal neurogenesis and alleviating depression-like behaviour in mice. These findings suggest that regulation of the hippocampal Tet1/DLL3/Notch1 protein pathway to influence neurogenesis may be a therapeutic strategy for depression.

Vitamin D and the epigenome: basic definitions, mechanisms and clinical effects

Epigenetic mechanisms play a crucial role in the regulation of gene expression. The underlying mechanisms include DNA methylation and covalent modification of histones by methylation, acetylation, phosphorylation, or ubiquitination. The complex interplay of various epigenetic mechanisms is mediated by enzymes operating in the cell nucleus. Modifications in DNA methylation are carried out primarily by DNA methyltransferases (DNMTs) and ten-eleven translocation proteins (TETs), while a variety of enzymes such as histone acetyltransferases (HATs), histone deacetylases (HDACs), histone methyltransferases (HMTs), and histone demethylases (HDMs)) regulate histone covalent modifications. In many pathological conditions such as cancer, autoimmune, microbial inflammatory, metabolic, allergic diseases and/or low vitamin D availability, the epigenetic regulatory system is often disrupted. Vitamin D interacts with the epigenome at several levels. First, critical genes in the vitamin D signaling system that encode for the vitamin D receptor (VDR) and the enzymes 25-hydroxylase (CYP2R1), 1α-hydroxylase (CYP27B1), and 24-hydroxylase (CYP24A1) have large CpG islands in their promoters. areas and therefore can be suppressed by DNA methylation. Second, the VDR protein physically interacts with coactivator and corepressor proteins, which in turn are in contact with chromatin modifiers such as HATs, HDACs, HMTS, and chromatin remodelers. Third, a number of genes encoding chromatin modifiers and remodelers, such as HDM from the Jumonji C (JmjC) domain containing proteins and lysine-specific demethylase (LSD) families, are primary targets for VDR and its ligands. Finally, there is evidence that certain VDR ligands have DNA demethylating effects. In this review, the authors discuss the regulation of the vitamin D system by epigenetic modifications and how vitamin D contributes to the maintenance of the epigenome and assess its impact on health and disease.

Using NMR to Monitor TET-Dependent Methylcytosine Dioxygenase Activity and Regulation.

The active removal of DNA methylation marks is governed by the ten-eleven translocation (TET) family of enzymes (TET1-3), which iteratively oxidize 5-methycytosine (5mC) into 5-hydroxymethycytosine (5hmC), and then 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). TET proteins are frequently mutated in myeloid malignancies or inactivated in solid tumors. These methylcytosine dioxygenases are α-ketoglutarate (αKG)-dependent and are, therefore, sensitive to metabolic homeostasis. For example, TET2 is activated by vitamin C (VC) and inhibited by specific oncometabolites. However, understanding the regulation of the TET2 enzyme by different metabolites and its activity remains challenging because of limitations in the methods used to simultaneously monitor TET2 substrates, products, and cofactors during catalysis. Here, we measure TET2-dependent activity in real time using NMR. Additionally, we demonstrate that in vitro activity of TET2 is highly dependent on the presence of VC in our system and is potently inhibited by an intermediate metabolite of the TCA cycle, oxaloacetate (OAA). Despite these opposing effects on TET2 activity, the binding sites of VC and OAA on TET2 are shared with αKG. Overall, our work suggests that NMR can be effectively used to monitor TET2 catalysis and illustrates how TET activity is regulated by metabolic and cellular conditions at each oxidation step.

Aerobic exercise alters DNA hydroxymethylation levels in an experimental rodent model of temporal lobe epilepsy

The therapeutic potential of aerobic exercise in mitigating seizures and cognitive issues in temporal lobe epilepsy (TLE) is recognized, yet the underlying mechanisms are not well understood. Using a rodent TLE model induced by Kainic acid (KA), we investigated the impact of a single bout of exercise (i.e., acute) or 4 weeks of aerobic exercise (i.e., chronic). Blood was processed for epilepsy-associated serum markers, and DNA methylation (DNAme), and hippocampal area CA3 was assessed for gene expression levels for DNAme-associated enzymes. While acute aerobic exercise did not alter serum Brain-Derived Neurotrophic Factor (BDNF) or Interleukin-6 (IL-6), chronic exercise resulted in an exercise-specific decrease in serum BDNF and an increase in serum IL-6 levels in epileptic rats. Additionally, whole blood DNAme levels, specifically 5-hydroxymethylcytosine (5-hmC), decreased in epileptic animals following chronic exercise. Hippocampal CA3 5-hmC levels and ten-eleven translocation protein (TET1) expression mirrored these changes. Furthermore, immunohistochemistry analysis revealed that most 5-hmC changes in response to chronic exercise were neuron-specific within area CA3 of the hippocampus. Together, these findings suggest that DNAme mechanisms in the rodent model of TLE are responsive to chronic aerobic exercise, with emphasis on neuronal 5-hmC DNAme in the epileptic hippocampus.

Egr2 Deletion in Autoimmune-Prone C57BL6/lpr Mice Suppresses the Expression of Methylation-Sensitive Dlk1-Dio3 Cluster MicroRNAs.

We previously demonstrated that the upregulation of microRNAs (miRNAs) at the genomic imprinted Dlk1-Dio3 locus in murine lupus is correlated with global DNA hypomethylation. We now report that the Dlk1-Dio3 genomic region in CD4+ T cells of MRL/lpr mice is hypomethylated, linking it to increased Dlk1-Dio3 miRNA expression. We evaluated the gene expression of methylating enzymes, DNA methyltransferases (DNMTs), and demethylating ten-eleven translocation proteins (TETs) to elucidate the molecular basis of DNA hypomethylation in lupus CD4+ T cells. There was a significantly elevated expression of Dnmt1 and Dnmt3b, as well as Tet1 and Tet2, in CD4+ T cells of three different lupus-prone mouse strains compared to controls. These findings suggest that the hypomethylation of murine lupus CD4+ T cells is likely attributed to a TET-mediated active demethylation pathway. Moreover, we found that deletion of early growth response 2 (Egr2), a transcription factor gene in B6/lpr mice markedly reduced maternally expressed miRNA genes but not paternally expressed protein-coding genes at the Dlk1-Dio3 locus in CD4+ T cells. EGR2 has been shown to induce DNA demethylation by recruiting TETs. Surprisingly, we found that deleting Egr2 in B6/lpr mice induced more hypomethylated differentially methylated regions at either the whole-genome level or the Dlk1-Dio3 locus in CD4+ T cells. Although the role of methylation in EGR2-mediated regulation of Dlk1-Dio3 miRNAs is not readily apparent, these are the first data to show that in lupus, Egr2 regulates Dlk1-Dio3 miRNAs, which target major signaling pathways in autoimmunity. These data provide a new perspective on the role of upregulated EGR2 in lupus pathogenesis.

TET2 is recruited by CREB to promote Cebpb, Cebpa, and Pparg transcription by facilitating hydroxymethylation during adipocyte differentiation

Ten-eleven translocation proteins (TETs) are dioxygenases that convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), an important epigenetic mark that regulates gene expression during development and differentiation. Here, we found that the TET2 expression was positively associated with adipogenesis. Further, invitro and invivo experiments showed that TET2 deficiency blocked adipogenesis by inhibiting the expression of the key transcription factors CCAAT/enhancer-binding protein beta (C/EBPβ), C/EBPα and peroxisome proliferator-activated receptor gamma (PPARγ). In addition, TET2 promoted 5hmC on the CpG islands (CGIs) of Cebpb, Cebpa and Pparg at the initial time point of their transcription, which requires the cAMP-responsive element-binding protein (CREB). At last, specific knockout of Tet2 in preadipocytes enabled mice to resist obesity and attenuated the obesity-associated insulin resistance. Together, TET2 is recruited by CREB to promote the expression of Cebpb, Cebpa and Pparg via 5hmC during adipogenesis and may be a potential therapeutic target for obesity and insulin resistance.

TET Family Members Are Integral to Porcine Oocyte Maturation and Parthenogenetic Pre-Implantation Embryogenesis.

The ten-eleven translocation (TET) enzyme family, which includes TET1/2/3, participates in active DNA demethylation in the eukaryotic genome; moreover, TET1/2/3 are functionally redundant in mice embryos. However, the combined effect of TET1/2/3 triple-gene knockdown or knockout on the porcine oocytes or embryos is still unclear. In this study, using Bobcat339, a specific small-molecule inhibitor of the TET family, we explored the effects of TET enzymes on oocyte maturation and early embryogenesis in pigs. Our results revealed that Bobcat339 treatment blocked porcine oocyte maturation and triggered early apoptosis. Furthermore, in the Bobcat339-treated oocytes, spindle architecture and chromosome alignment were disrupted, probably due to the huge loss of 5-hydroxymethylcytosine (5hmC)and concurrent increase in 5-methylcytosine (5mC). After Bobcat339 treatment, early parthenogenetic embryos exhibited abnormal 5mC and 5hmC levels, which resulted in compromised cleavage and blastocyst rate. The mRNA levels of EIF1A and DPPA2 (ZGA marker genes) were significantly decreased, which may explain why the embryos were arrested at the 4-cell stage after Bobcat339 treatment. In addition, the mRNA levels of pluripotency-related genes OCT4 and NANOG were declined after Bobcat339 treatment. RNA sequencing analysis revealed differentially expressed genes in Bobcat339-treated embryos at the 4-cell stage, which were significantly enriched in cell proliferation, cell component related to mitochondrion, and cell adhesion molecule binding. Our results indicated that TET proteins are essential for porcine oocyte maturation and early embryogenesis, and they act by mediating 5mC/5hmC levels and gene transcription.

5hmC modification regulates R-loop accumulation in response to stress.

R-loop, an RNA-DNA hybrid structure, arises as a transcriptional by-product and has been implicated in DNA damage and genomic instability when excessive R-loop is accumulated. Although previous study demonstrated that R-loop is associated with ten-eleven translocation (Tet) proteins, which oxidize 5-methylcytosine to 5-hydroxymethylcytosine (5hmC), the sixth base of DNA. However, the relationship between R-loop and DNA 5hmC modification remains unclear. In this study, we found that chronic restraint stress increased R-loop accumulation and decreased 5hmC modification in the prefrontal cortex (PFC) of the stressed mice. The increase of DNA 5hmC modification by vitamin C was accompanied with the decrease of R-loop levels; on the contrary, the decrease of DNA 5hmC modification by a small compound SC-1 increased the R-loop levels, indicating that 5hmC modification inversely regulates R-loop accumulation. Further, we showed that Tet deficiency-induced reduction of DNA 5hmC promoted R-loop accumulation. In addition, Tet proteins immunoprecipitated with Non-POU domain-containing octamer-binding (NONO) proteins. The deficiency of Tet proteins or NONO increased R-loop levels, but silencing Tet proteins and NONO did not further increase the increase accumulation, suggesting that NONO and Tet proteins formed a complex to inhibit R-loop formation. It was worth noting that NONO protein levels decreased in the PFC of stressed mice with R-loop accumulation. The administration of antidepressant fluoxetine to stressed mice increased NONO protein levels, and effectively decreased R-loop accumulation and DNA damage. In conclusion, we showed that DNA 5hmC modification negatively regulates R-loop accumulation by the NONO-Tet complex under stress. Our findings provide potential therapeutic targets for depression.

Melatonin: A Potential Regulator of DNA Methylation.

The pineal gland-derived indoleamine hormone, melatonin, regulates multiple cellular processes, ranging from chronobiology, proliferation, apoptosis, and oxidative damage to pigmentation, immune regulation, and mitochondrial metabolism. While melatonin is best known as a master regulator of the circadian rhythm, previous studies also have revealed connections between circadian cycle disruption and genomic instability, including epigenetic changes in the pattern of DNA methylation. For example, melatonin secretion is associated with differential circadian gene methylation in night shift workers and the regulation of genomic methylation during embryonic development, and there is accumulating evidence that melatonin can modify DNA methylation. Since the latter one impacts cancer initiation, and also, non-malignant diseases development, and that targeting DNA methylation has become a novel intervention target in clinical therapy, this review discusses the potential role of melatonin as an under-investigated candidate epigenetic regulator, namely by modulating DNA methylation via changes in mRNA and the protein expression of DNA methyltransferases (DNMTs) and ten-eleven translocation (TET) proteins. Furthermore, since melatonin may impact changes in the DNA methylation pattern, the authors of the review suggest its possible use in combination therapy with epigenetic drugs as a new anticancer strategy.

Epidrugs in the Therapy of Central Nervous System Disorders: A Way to Drive on?

The polygenic nature of neurological and psychiatric syndromes and the significant impact of environmental factors on the underlying developmental, homeostatic, and neuroplastic mechanisms suggest that an efficient therapy for these disorders should be a complex one. Pharmacological interventions with drugs selectively influencing the epigenetic landscape (epidrugs) allow one to hit multiple targets, therefore, assumably addressing a wide spectrum of genetic and environmental mechanisms of central nervous system (CNS) disorders. The aim of this review is to understand what fundamental pathological mechanisms would be optimal to target with epidrugs in the treatment of neurological or psychiatric complications. To date, the use of histone deacetylases and DNA methyltransferase inhibitors (HDACis and DNMTis) in the clinic is focused on the treatment of neoplasms (mainly of a glial origin) and is based on the cytostatic and cytotoxic actions of these compounds. Preclinical data show that besides this activity, inhibitors of histone deacetylases, DNA methyltransferases, bromodomains, and ten-eleven translocation (TET) proteins impact the expression of neuroimmune inflammation mediators (cytokines and pro-apoptotic factors), neurotrophins (brain-derived neurotropic factor (BDNF) and nerve growth factor (NGF)), ion channels, ionotropic receptors, as well as pathoproteins (β-amyloid, tau protein, and α-synuclein). Based on this profile of activities, epidrugs may be favorable as a treatment for neurodegenerative diseases. For the treatment of neurodevelopmental disorders, drug addiction, as well as anxiety disorders, depression, schizophrenia, and epilepsy, contemporary epidrugs still require further development concerning a tuning of pharmacological effects, reduction in toxicity, and development of efficient treatment protocols. A promising strategy to further clarify the potential targets of epidrugs as therapeutic means to cure neurological and psychiatric syndromes is the profiling of the epigenetic mechanisms, which have evolved upon actions of complex physiological lifestyle factors, such as diet and physical exercise, and which are effective in the management of neurodegenerative diseases and dementia.

Glut10 restrains neointima formation by promoting SMCs mtDNA demethylation and improving mitochondrial function

Neointimal hyperplasia is a major clinical complication of coronary artery bypass graft and percutaneous coronary intervention. Smooth muscle cells (SMCs) play a vital roles in neointimal hyperplasia development and undergo complex phenotype switching. Previous studies have linked glucose transporter member 10(Glut10) to the phenotypic transformation of SMCs. In this research, we reported that Glut10 helps maintain the contractile phenotype of SMCs. The Glut10-TET2/3 signaling axis can arrest neointimal hyperplasia progression by improving mitochondrial function via promotion of mtDNA demethylation in SMCs. Glut10 is significantly downregulated in both human and mouse restenotic arteries. Global Glut10 deletion or SMC-specific Glut10 ablation in the carotid artery of mice accelerated neointimal hyperplasia, while Glut10 overexpression in the carotid artery triggered the opposite effects. All of these changes were accompanied by a significant increase in vascular SMCs migration and proliferation. Mechanistically, Glut10 is expressed primarily in the mitochondria after platelet-derived growth factor-BB (PDGF-BB) treatment. Glut10 ablation induced a reduction in ascorbic acid (VitC) concentrations in mitochondria and mitochondrial DNA (mtDNA) hypermethylation by decreasing the activity and expression of the Ten-eleven translocation (TET) protein family. We also observed that Glut10 deficiency aggravated mitochondrial dysfunction and decreased the adenosinetriphosphate (ATP) content and the oxygen consumption rate, which also caused SMCs to switch their phenotype from contractile to synthetic phenotype. Furthermore, mitochondria-specific TET family inhibition partially reversed these effects. These results suggested that Glut10 helps maintain the contractile phenotype of SMCs. The Glut10-TET2/3 signaling axis can arrest neointimal hyperplasia progression by improving mitochondrial function via the promotion of mtDNA demethylation in SMCs.

High Expression of Ten Eleven Translocation 1 Is Associated with Poor Prognosis in Hepatocellular Carcinoma.

DNA methylation patterns have been found to be distinct between tumor and normal patients. However, the effect of DNA demethylation enzymes, ten eleven translocation (TET) proteins, has not been comprehensively characterized in liver cancer. In this research, we sought to unravel the linkage of TET proteins with prognosis, immune characteristics and biological pathways in hepatocellular carcinoma (HCC). Four independent datasets with gene expression data and clinical data of HCC samples were downloaded from public databases. CIBERSORT, single sample Gene Set Enrichment Analysis (ssGSEA), MCP-counter, and TIMER were implemented to evaluate immune cell infiltration. limma was employed to screen differentially expressed genes (DEGs) between two groups. The demethylation-related risk model was established by using univariate Cox regression analysis, the least absolute shrinkage and selection operator (LASSO), and stepwise Akaike information criterion (stepAIC). TET1 was significantly higher expressed in tumor samples than that in normal samples. HCC patients with advanced stages (III+IV) and grades (G3+G4) had higher TET1 expression compared to early stages (I+II) and grades (G1+G2). HCC samples with high TET1 expression had worse prognosis than that with low expression. High and low TET1 expression groups had distinct immune cell infiltration and response to immunotherapy and chemotherapy. We identified 90 DEGs related to DNA demethylation in high vs. low TET1 expression groups. Furthermore, we established a risk model based on 90 DEGs containing seven key prognostic genes (SERPINH1, CDC20, HACD2, SPHK1, UGT2B15, SLC1A5, and CYP2C9) with effectiveness and robustness in predicting HCC prognosis. Our study suggested TET1 as a potential indicator in HCC progression. TET1 was closely involved in immune infiltration and activation of oncogenic pathways. The DNA demethylation-related risk model was potential to be applied for predicting HCC prognosis in clinics.

TET3 as a non-invasive screening tool for the detection of fibrosis in patients with chronic liver disease

Ten-eleven translocation protein 3 (TET3) is one of the key enzymes in DNA demethylation which can be expressed in liver tissues. However, the clinical value of TET3 for diagnosis and treatment of chronic liver disease have not been reported previously. We investigated the diagnostic accuracy of serum TET3 as a non-invasive screening tool for liver fibrosis. 212 patients with chronic liver disease from were enrolled in this study. Enzyme-linked immunosorbent assay was used to measure the serum levels of TET3. Receiver operating characteristics (ROC) were determined to examine the diagnostic accuracy of TET3 and combination model for diagnosis fibrosis. Serum TET3 level in fibrosis cases was significantly higher than that in non-fibrosis and controls, respectively. The areas under the ROC curve of the TET3 and fibrosis-4 index for liver fibrosis were 0.863 and 0.813, and 0.916 and 0.957 for liver cirrhosis. The combination of TET3 and fibrosis-4 index had a highly promising positive predictive value for detecting liver fibrosis and cirrhosis different stages of (93.5% and 100%) as compared with each diagnostic tool alone. TET3 is related to the development of liver fibrosis and cirrhosis. The TET3-fibrosis-4 model enhances discriminatory power and represents a promising non-invasive tool for the diagnosis and screening of liver fibrosis.

Abstract 2226: Modeling the role of Tet-deficiency and restoration in Bcl2-driven B cell lymphoma progression

Abstract Loss of function in DNA methylation regulators such as the Ten-eleven translocation (TET1-3) proteins, have been implicated in the progression of lymphoma. TET enzymes constitute a family of iron and αKG-dependent dioxygenases that oxidize 5-methylcytosine in DNA to promote demethylation and the reversal of gene silencing. The TET enzymes require vitamin C for their optimal catalytic activity, however, many patients with hematological malignancies are vitamin C deficient. Enhancing and restoring TET function with high-dose vitamin C has been shown to block the progression of solid tumors and blood malignancies. A combination of genetic and epigenetic diversity in lymphoma can result in the aberrant overexpression of oncogenes, loss of tumor suppressor function, and genomic instability. Our research models Bcl2-driven B cell lymphoma with Tet-deficiency using transgenic RNAi for the knockdown of Tet1 or Tet2. In vitro, our results have shown that this model shows increased self-renewal capacity of early B cell progenitors and precursors that can be suppressed by genetic restoration of Tet expression or upon treatment with vitamin C. In vivo, the B cell compartment of mice with Bcl2 overexpression and Tet1 or Tet2 deficiency exhibit a block in B cell maturation during a long period of pre-malignancy, and a decreased frequency of follicular B cells in the spleen from 3 months of age. Our aim is to determine mechanistically the effects of Tet-deficiency on B cell lymphoma progression and whether vitamin C can restore Tet activity to suppress lymphoma progression. Citation Format: Minh Quang Lam, Luisa Cimmino. Modeling the role of Tet-deficiency and restoration in Bcl2-driven B cell lymphoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2226.